It still does not look like window light to me...the "behind the scenes look" Iron Flatline mentioned having no lights in sight....well, she's sitting on a posing stool in front of a seamless backdrop, and all we see is two to three feet to the side of her...that doesn't by necessity mean the lighting is automaticvally "windows'. I can see a square catchlight in each eyeball, and on the right hand side, the catchlight appears to be rounded...I wonder if he has round windows??? WIndows reflected or lights shining or strobes popping--all thrtee types of sources produce "catchlights".
The clue that these are shot with flash and not window light that I see is the degree of specularity on her nose, and forehead, as well as on the "valley" of her upper lip...see that bright,crisp, white highlight on her lip, right below the nose? That crisp, WHITE delineation is specularity that is typical of studio flash used with fabric-based modifiers. Same with the big, bright forehead highlight she has. Of course, an image shot with window light can be "lifted" in Photoshop, and made to look similar, by elevating the mid-tones upward to the extent that the shadows become very open, and some degree of specularity is gained on the high points of the face, chin, ears, forehead, etc.
If she's sitting on a seamless paper sweep on a posing stool, and the lighting is THAT shadowless, and also that specular, it looks (to me at least) very much light a large panel is the main light, and a close-by large-ish umbrella or octabox is acting as the fill light in what's called side-by-side lighting. It's popular for beauty work, and easy to work with. Of course, it could be window light...but there are several things that make me think it's not. Specularity, the way the shadows are very open, and the size of the catchlights on the eyeball in relation to her...of course, he could be working in a natural light studio that has those huge, expansive windows, and just using a round umbrella or round reflector close to her as a fill source, just bouncing some light onto her face. This just "feels" to me like strobe, not daylight. Of course, in the hands of a skilled shooter, daylight can look like this--plus there is also the professional-level post work that these types of shots are subjected to as standard.